html {
    scroll-behavior: smooth;
}
.sticky {
    position: fixed;
    top: 100px;
    width: 300px;
}

.footer-reached {
    position: absolute;
    bottom: 0;
}

@media (max-width: 480px) {
    .sticky {
        position: relative;
        top: inherit;
        width: auto;
    }
}